EAGER: Testing the Roles of Zygotic Selection and Sperm Competition in Transmission Bias in Astyanax

精子的特征是由产生精子的雄性的二倍体基因型决定的，这一观点已经被接受。 然而，最近出乎意料的发现表明，精子细胞的表型也可能受到其自身基因型的影响。这个创新的项目研究了精子细胞的单倍体基因型影响其个体特征的程度，以及精子竞争与受精后选择在等位基因从一代到下一代的传递中引起偏差的相对重要性。它将提供基本的信息，以阐明一个以前未被怀疑，但潜在的重要途径，自然选择在进化中。预期的结果有可能在精子生物学研究中开辟一条重要的新路线。他们预计将有广泛的影响，在发育生物学，进化生物学，并在人类和家畜的繁殖技术的改进。本研究探讨了基因间的上位相互作用观察到的两个早期物种的淡水鱼（Astyanax spp.）之间的杂交。先前的研究表明，来自杂交雄性的精子传递沿着有偏见的等位基因子集和来自非连锁基因的等位基因组合。这一观察结果提出了一个假设，即个体精子的表型（在这种情况下是受精效率）是由其个体基因型决定的，即，包裹被递送的概率取决于它包含的内容。与这一假设相一致的是，初步研究表明，精子亚群--由游泳能力的差异或对化学挑战的反应来定义--在等位基因含量上存在显着差异。这项研究测试所观察到的传输偏差是否确实是由精子竞争引起的，或者是否有受精后合子选择的贡献。将从使用卵胞浆内单精子注射形成的胚胎中对单个精子进行基因分型。这将允许比较不同的精子亚群（例如，慢泳者与快泳者）的等位基因含量。此外，将对杂种X非杂种个体的后代进行基因分型，以检测传播偏倚。该假说预测，偏见将仅限于家庭来自杂交男性，而不是来自杂交女性。

It has been accepted that the characteristics of sperm are determined by the diploid genotype of the male producing them. However, recent and unexpected findings indicate that the phenotype of a sperm cell may also be influenced by its own genotype. This innovative project examines the degree to which the haploid genotypes of sperm cells affect their individual characteristics and the relative importance of sperm competition versus selection post-fertilization in causing biases in transmission of alleles from one generation to the next. It will provide basic information to illuminate a previously unsuspected but potentially important avenue for natural selection in evolution. The expected results have the potential to open up an important new line of research in sperm biology. They are expected to have broad implications in developmental biology, evolutionary biology, and for improvements in reporductive technologies in humans and domestic animals.This research investigates the epistatic interactions among genes observable in hybrids between two incipient species of freshwater fish (Astyanax spp.). Previous work has shown that sperm from hybrid males pass along biased subsets of alleles and allelic combinations derived from unlinked genes. This observation suggested the hypothesis that the phenotypes of individual sperm (in this case fertilization efficiency) are determined by their individual genotypes, i.e., the probability that a package gets delivered depends upon what it contains. Consistent with this hypothesis are preliminary studies that show that sperm subpopulations - defined by differences in swimming ability or by their response to a chemical challenge - differ significantly in allelic content. This research tests whether the observed transmission biases are indeed caused by sperm competition or whether there is a contribution from zygotic selection, post fertilization. Single sperm will be genotyped from embryos formed using intracytoplasmic sperm injection. This will allow different sub-populations of sperm (e.g. slow versus fast swimmers) to be compared for allelic content. Additionally, the offspring of hybrid X non-hybrid individuals will be genotyped, allowing for the detection of transmission biases. The hypothesis predicts that biases will be restricted to families derived from hybrid males but not from hybrid females.